Jet streams are narrow bands of strong wind that generally blow from west to east all across the globe, and they form high in the atmosphere where warm air masses meet cold air masses, and Earth has four primary jet streams: two polar ones near the poles and two subtropical ones closer to the equator. On average, jet streams move at about 110 miles per hour, so a flight from west to east can generally be faster than the same route from east to west, because the jet stream blows from west to east. Earth's atmosphere is a thin layer, and if Earth were the size of a basketball, a tightly held pillowcase would be as thick as the atmosphere. Thin air at high altitude means less drag, but a plane needs enough air to make lift.

Every airplane has six basic instruments: the airspeed indicator, attitude indicator, altimeter, turn coordinator, heading indicator and vertical speed indicator, and they let pilots fly safely even when they cannot see the ground or the horizon. The altimeter, airspeed indicator and vertical speed indicator work from air pressure measured by a Pitot-static tube, while the heading indicator, attitude indicator and turn coordinator work from gyroscopes. An airplane rotates about its center of gravity, the average location of its mass, and roll, pitch and yaw are all turns about that point. The elevators control pitch, the rudder controls yaw, and the ailerons control roll. The two-axis autopilot in most small airplanes controls the aircraft's pitch and roll. It can hold a heading and altitude, or it can be coupled to a navigation system and fly a programmed course.

Aluminum is used on most aircraft because it is lightweight and strong, but it loses strength at high temperatures, so it cannot be used for skin that gets very hot on airplanes flying faster than twice the speed of sound. Graphite-epoxy is a composite material made of strong graphite fibers set in epoxy resin, and it is about as strong as aluminum and weighs about half as much, so it is used more and more for aircraft parts. Engineers use wind tunnels to test new aircraft designs, new materials, new shapes for airplane parts, and even how to keep ice from forming on wings. In some wind tunnels, models are held in place by magnetic fields, so they do not have to be mounted on stands that would disturb the airflow.

The Concorde was the first turbojet-powered supersonic airliner to enter service flying passengers across the Atlantic at twice the speed of sound, and Air France and British Airways together began Concorde service in 1976. The plane flew from New York to London in under three hours, compared with about seven hours on a regular airliner as of November 2026. Jet passenger service in the United States had begun in the late 1950s with the Boeing 707 and the Douglas DC-8. The Concorde cruised between 55,000 and 60,000 feet, so high that passengers could see the curve of the Earth. Because of its speed, the aluminum skin heated to over 120 degrees Celsius in flight, and the plane stretched about 8 inches in length. The Concorde carried only 92 to 128 passengers. High operating costs meant very high fares that few could afford, and all Concordes were retired in 2003.

A wing has a rounded front edge because a rounded leading edge divides the air smoothly even when the wing is tilted. Air cannot turn a sharp corner, so a sharp leading edge would disrupt the flow, cut lift and add drag. Airplane wings are shaped so that a wing meeting the air pushes the air down, and the air pushes the wing up. Lift is made when a wing turns the air: the air is bent in one direction and the wing is pushed in the opposite direction, as Newton's third law says. Jet engines make thrust by raising the pressure inside the engine. That pressure pushes harder on the front of the engine than on the rear, so the net force is forward.

The Boeing 747 entered service in 1970 and carried more than twice as many passengers as the 189-seat 707, with about 400 seats and much lower seat-mile costs. As of November 2026, the Airbus A380 is the largest passenger plane ever built, about 73 meters long with a wingspan of nearly 80 meters. It is the only full-length double-deck airliner and can carry over 850 passengers in an all-economy layout. Since it entered commercial service in 2007, the A380 has flown over 800,000 flights and carried more than 300 million passengers, as of November 2026.

Words to know

• gyroscopes: spinning direction sensors
• altimeter: height meter
• composite: mixed material
• supersonic: faster than sound
• autopilot: holds a course